Improvement of Distribution Feeder Loss and Voltage Profile (Case Study: Bella Substation Distribution Feeder)

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Addis Ababa University


Distribution feeders are components of distribution system which transfer power from distribution substation to distribution transformers located near to customer’s premises. Distribution substation feeders which have poor power factor, large loads beyond its’ carrying capacity and which travel long distance to feed costumers are not efficient in transferring electrical power to the connected costumers. To improve the efficiency of distribution feeders in terms of power loss and voltage profile, loss minimization and voltage profile improvement techniques are required. Bella distribution substation is one of the distribution substations found in Addis Ababa Ethiopia which has six outgoing feeders that feed different areas. Among these feeders, feeder four F4 has been selected as test system due to its longest rout length and large loads during a year recorded data. The selected feeder has been modeled in MATLAB computational tool and DIgSILENT simulating software and load flow analysis has been simulated using Newton-Raphson method implemented in MATLAB. From Newton-Raphson load flow simulation of feeder F4, it has been observed that the feeder has a power loss of 3.86MW and voltage drop up to 0.3pu at peak load. To reduce power loss and voltage drop of this feeder, capacitors and distributed generation units have been suggested and the impact is investigated. To find optimal size and location of the capacitors and DG, particle swarm optimization (PSO) and genetic algorithm (GA) have been implemented in MATLAB. PSO based capacitor placement resulted in a placement of capacitor sizes(kVAr) (970, 290, 2690, 1350, 1110, 120, 370, 1070, 320) on buses of F4(36, 62, 34, 35, 37, 61, 59, 51, 50) respectively. PSO based DG placement resulted in a placement of DG sizes (kw) (530.1, 255.6, 241.5, 355.2, 399.9, 321.9, 176.6, 385) on buses of F4(62, 61, 60, 59, 32, 31, 27, 24) respectively and GA based capacitor placement resulted in a placement of capacitors sizes(kVAr) (1041.8, 540.3, 1599.7, 1930.6, 1415.2, 26.2, 72, 234.2, 767.2, 858.9) on buses (36, 62, 34, 35, 37, 61, 60, 59, 51, 50) respectively. The initial capital investment cost of PSO based capacitor, PSO based DG and GA based capacitor placement on F4 requires 3,317,328 Birr, 184,114,566 Birr and 6,698,160 Birr with respective return of investment 0.1664 year, 6.832 years and 0.3361 year respectively. Peak load Newton-Raphson load flow simulation of F4 after separate placement of PSO based capacitor, PSO based DG and GA based capacitor results in power loss and voltage drop reduction of (37.3%, 15%), (50%, 12%) and (37.2%, 15.7%) respectively. In addition to peak load, the load flow was simulated at load level of 83% of peak load, 60% of peak load and base load. In general, for power loss reduction and voltage profile improvement of distribution feeders, PSO based capacitor placement is recommended due to the reasonably minimum capital investment and better performance improvement in reduction of power loss and voltage drop.



Distribution system power loss, voltage drop, PSO based capacitor placement, DG, PSO, GA